What are the pros and cons of anaerobic sewage treatment?

Anaerobic treatment of industrial wastewater is a tried-and-true, low-energy method. In an oxygen-free environment, anaerobic bacteria convert organic pollutants or COD (chemical oxygen demand), into biogas.

Anaerobic microorganisms (those that thrive in oxygen-free environments) are chosen for their ability, to degrade organic matter in effluents, converting organic pollutants into biogas (methane + carbon dioxide) and a trace of bio-solids. The high-energy biogas can then be used as boiler feed or combined heat and power (CHP), to generate 'green' electricity and heat.

The advantages and disadvantages of anaerobic sewage treatment

Some of the benefits are as follows:

(1)   Simplicity of operation and maintenance;

(2)   Lower capital expenditures;

(3)   Lower biochemical oxygen demand (BOD) and phosphorus in the supernatant;

(4)   Less impact from disturbances such as harmful interferences, or variations in loading and pH;

(5)   There is less odour;

(6)   Non-detonating;

(7)   Lower levels of soluble grease and hexane;

(8)   Increased sludge fertilizer value;

(9)   Shorter retention times;

(10)    A viable alternative for small wastewater treatment plants;

(11)    Lower sludge treatment and disposal costs because, biomass production is six to eight times lower than aerobic processes;

(12)    Lower nutrient supplementation costs because fewer nutrients are required,due to lower biomass production;

(13)    Anaerobic systems generate biomass, which can be used as an alternative fuel source;

(14)    Anaerobic systems respond quickly to substrates after a long period of inactivity.

Some of the disadvantages are as follows:

(1)   Extremely temperature-sensitive;

(2)   Higher operating costs, particularly energy costs;

(3)   No beneficial by-products, such as methane gas, are produced by anaerobic digestion;

(4)   The ability to dewater in order to reduce sludge volume;

(5)   Less volatile solids decrease;

(6)   Larger wastewater treatment plants have poor economics.

Usage of anaerobic sewage treatment

Anaerobic wastewater treatment is used to treat a wide range of industrial effluent streams, including agricultural, food and beverage, dairy, pulp and paper, and textile effluent, as well as municipal sewage sludge and wastewater.

Anaerobic technologies are typically used before aerobic treatment, in streams with high concentrations of organic material (measured as high BOD, COD, or TSS). Anaerobic treatment is also used for specialized applications, such as the treatment of waste streams containing inorganics or chlorinated organics, and it is well suited for the treatment of warm industrial wastewater.

Conclusion

Anaerobic wastewater treatment is well-known for its efficient, low-odour treatment of streams, containing high concentrations of organic contaminants. In the absence of oxygen, microorganisms degrade organic contaminants in anaerobic wastewater treatment.

Anaerobic wastewater treatment can be used to treat liquid organic wastewaters, ranging from dilute to concentrated, distillery, brewery, food and beverage industry, paper manufacturing, petrochemical, etc. Even municipal wastewater (sewage) can be treated using anaerobic technologies in tropical countries.

How can we assist?

Netsol Water can provide anaerobic wastewater treatment, using existing anaerobic sludge treatment systems. We provide anaerobic wastewater treatment plant design, engineering, and implementation, as well as laboratory scale and pilot testing of anaerobic technology, and combinations of anaerobic and Membrane Bioreactor (MBR) technology.

We customize each system to the needs of its clients, with each unit developed and constructed to order.